Gildford Colony

What EPA’s and Montana’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves: 70 people
Connections: 10
Water source: Groundwater
Based in: Gildford, MT
County: Hill
Owner: Private

The ZIP code it serves

59525

The short answer

Nothing in EPA’s and Montana’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Fluoride, nitrate, arsenic and chromium (total): Montana’s own results, samples taken from Jan. 8, 2020 to Jan. 5, 2026, with EPA’s 2012 to 2019 file for earlier years.

Haloacetic acids (HAA5), total trihalomethanes (TTHM) and uranium: EPA’s compliance monitoring file, samples taken from Jan. 7, 2013 to Feb. 22, 2017. Newer results are in the utility’s annual water quality report.

Below EPA’s limits2

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.066ppm

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 0.066 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. In 2025, the latest year on file, it wasn’t found in its one sample.

What handles it

NSF/ANSI 58 look for “Fluoride Reduction”
NSF/ANSI 53 look for “Fluoride”

Nitrate

Comes from the source

Below EPA’s limits

0.046ppm

Highest sample; found in 2 of 7

2026, one sample: 0.008 ppm

The highest sample, in 2024, was 0.046 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its one sample was 0.008 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.005 ppm, in 2019.

What handles it

NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

6 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Chromium (total)
Haloacetic acids (HAA5)
Lead
Total trihalomethanes (TTHM)
Uranium

Violations since 2016

No health-based violations on file with EPA since 2016. There are 3 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

Everything else. Fluoride, nitrate, arsenic and chromium (total) results here are Montana’s own from 2020 on, with EPA’s national file for 2012 to 2019. Haloacetic acids (HAA5), total trihalomethanes (TTHM) and uranium come from EPA’s file alone, which ends in 2019. Gildford Colony’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; Montana’s results run from Jan. 8, 2020 to Jan. 5, 2026; EPA’s compliance samples are from Jan. 7, 2013 to Feb. 22, 2017.

Testing your own tap

Gildford Colony’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Montana certifies.

No lab Montana certifies is within 75 miles of the area Gildford Colony serves on the state’s list. Some take samples by mail; the state’s page lists them all.

Montana State Environmental Laboratory: Private well testing packages for bacteria, metals, nutrients, anions, organic chemicals and more, open to the public. Samples can be mailed, sent by the lab's free courier, or dropped off at the lab. Environmental Laboratory, Montana Department of Public Health and Human Services.

All 36 certified labs for Montana